This invention relates generally to novel methods, apparatuses, and compositions of matter useful in controlling the corrosion of slurry transporting pipelines. As described for example in U.S. Pat. Nos. 8,168,071, 6,586,497, 5,709,731, 4,624,680, 4,546,612, 4,282,006 and 4,206,610, the transport of many slurries (such as ore slurries) is commonly accomplished using mild steel pipelines. Essentially, the ore is grinded and mixed with water in order to form a mud that can then be pumped through the pipeline. These pipelines are therefore subjected to both corrosive and erosive effects. Corrosion is a very well know process by which a chemical reaction takes place on the surface of the metallic material. As a result of this reaction there is a loss of material from the metal surface to the medium in contact which such metal. From practical point of view this phenomenon damages the equipment and reduces its useful lifetime.
Erosion is also a well-known phenomenon by which a mechanical agent physically removes material from a certain surface due to repeated abrasive impacts against the surface. The final consequence also is equipment damage and reduction of useful lifetime.
When slurries are transported through a pipeline, both corrosion and erosion act against the pipeline. Even worse, when both are present each of the two processes enhances the damaging effect of the other, resulting in an even worse synergy between the two. This synergy results in a loss of pipeline material during slurry transport which is larger than the sum of the loss of material caused by erosion and loss of material cause by corrosion. This detrimental effect is commonly referred to as “corrosion-erosion”.
The prior art contains a number of strategies for separately addressing corrosion and separately addressing erosion. The prior art however lacks a strategy that directly and efficiently addresses corrosion-erosion when erosion component is aggressive enough to remove the protective layer provided by the corrosion inhibitor and instead relies upon ever greater applications of erosion countering strategies with corrosion countering strategies. Corrosion is commonly addressed by adding to the slurry a corrosion inhibitor whose chemical properties competes with or neutralizes the chemical reactions causing corrosion. Erosion is commonly handled by the careful choice of types and amounts of materials used to make the pipeline components. Often this involves the combination of layered materials and sometimes special coatings over the pipe surfaces.
Prior art combinations of anti-corrosion with anti-erosion strategies, such as those described in U.S. Pat. Nos. 4,935,195, 4,779,453, and 7,398,193 and Japanese Application Patent Laid-Open Publication No. Hei 8-178172 unfortunately suffer from at least two drawbacks. First, they rely upon expensive erosion resistant piping and the constant the need to replace this piping drastically raises the cost of constructing and maintaining pipelines. In addition, it is difficult to impossible to replace many sections of pipelines without imposing major delays and reductions in the operation of slurry transporting activities. In fact, some pipe sections cannot be replaced without completely removing major sections of the pipeline and are therefore cost prohibitive.
Accordingly, there is an ongoing need for a method of reducing corrosion-erosion that does not involve replacing pre-existing sections of pipeline. The art described in this section is not intended to constitute an admission that any patent, publication or other information referred to herein is “Prior Art” with respect to this invention, unless specifically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 CFR §1.56(a) exists.